The invention relates to a method for the separation of mixed fluid media in which a phase boundary formed between the separated media is detected.
Such methods are used in particular in conjunction with separation chambers in which media with different physical properties, in particular with different optical properties and in particular with different extinction coefficients, are separated from each other and the media distribution present in the separation chamber is to be detected. Thus, it is known from U.S. Pat. No. 3,955,755 to measure an integral optical signal which is obtained by subjecting a measuring window at the phase boundary between two media to an interrogation beam, and to use this measuring signal itself as actual value for a control for the separation of the media. In such methods, disturbances such as for example fluctuations of the optical properties, for example of the extinction, caused for example by soiling of the measuring window or aging of the optical transmitter, are incorporated completely into the measured result and thus into the control circuit. This makes frequent adjustments of the zero point of the separation necessary. A further possible error results from any change in the intensity during the separation.
An object of the invention is to provide a method and apparatus for the separation of mixed fluid media such that very rapid, trouble-free and adjustment-free control of the separation process is achieved.